add a function to determine if an x,y pair is in a vd
add a function to determine if an x,y pair is in a vd

this will be used to determine selection in graphmanager, you shouldn't use
this unless you're insane because graphmanager will do it for you

Signed-off-by: Sam Phippen <e5a09176608998a68778e11d5021c871e8fae93c@googlemail.com>

samphippen/spe,samphippen/spe,samphippen/spe,samphippen/spe